1. Technical Field
The present disclosure relates to a voltage boosting circuit and a voltage boosting/dropping circuit that use a direct current-to-direct current (DC-DC) converter boosting or dropping an input voltage according to frequency setting information of input clock signals, and a liquid crystal display (LCD).
2. Discussion of Related Art
A voltage boosting circuit or a voltage boosting/dropping circuit, which uses a DC-DC converter, has been widely used for various electronic appliances requiring driving voltages.
A DC-DC converter acquires a desired predetermined voltage by boosting or dropping a supply voltage according to input clock signals and typically includes a circuit formed by combining a transistor, a condenser and the like. When such a DC-DC converter operates, starting control is performed, in which clock signals having a predetermined frequency are input to the DC-DC converter, so that the desired predetermined voltage can be obtained from the DC-DC converter.
The starting control of such a DC-DC converter is a problem, however because the clock signals having a predetermined frequency are simply input to the DC-DC converter.
Thus, because the output voltage of the DC-DC converter is a low voltage during the starting of the DC-DC converter, an operation of the DC-DC converter is unstable until the DC-DC converter obtains the desired output voltage, even if the clock signals having a predetermined frequency are input thereto. That is, the conventional starting control of the DC-DC converter is not performed according to a boosting operation or a dropping operation when the DC-DC converter starts to operate.